Anodizing method of aluminum and aluminum product

ABSTRACT

According to an aspect of the present invention, there is provided an aluminum product. The Aluminum product may comprise an aluminum substrate configured to include a pattern and a white aluminum fluoride (AlF 3 ) film on a surface thereof; and an anodized film configured to be disposed adjacent to the white aluminum fluoride (AlF3) film and include a plurality of pores.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2016-0041472, filed on Apr. 5, 2016 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND 1. Field

Embodiments of the present disclosure relate to a method of anodizing aluminum and an aluminum product manufactured thereby, and more specifically to a white anodizing method of aluminum or an aluminum alloy; and an aluminum product manufactured thereby.

2. Description of the Related Art

Aluminum and aluminum alloys have a variety of industrial applications. However, due to the reactivity, corrosion tendency, harmfulness, and the like that aluminum possesses, aluminum and aluminum alloys need a corrosion-resistant, protective coating provided on an exposed surface thereof. Also, when the appearance of a manufactured article is considered important, a surface of aluminum or an aluminum alloy is dyed after anodization, in which case, the light stability needs to be enhanced.

Conventionally, to provide a surface of aluminum or an aluminum alloy with a film that helps to maintain corrosion resistance and long-term whiteness, methods of forming an anodized film on the aluminum or aluminum alloy and then coloring an inside of the film with a white pigment have been attempted. Also, methods of forming an opaque anodized film capable of light diffusion by varying current density during the anodization of aluminum or an aluminum alloy have been attempted.

Meanwhile, when the appearance of the manufactured article is considered important, methods of immersing aluminum or an aluminum alloy in an aqueous dye solution during a process of coloring a surface of the aluminum or aluminum alloy with the dye after anodization have been tried for light stability enhancement.

SUMMARY

Therefore, it is an aspect of the present disclosure to provide a method of anodizing aluminum that includes a process of forming a white aluminum fluoride film; and an article manufactured thereby.

Another aspect of the present disclosure provides a method of anodizing aluminum that is configured to induce the polymerization of a dye and an acrylic resin so as to reduce discoloration caused by light; and an article manufactured thereby.

According to an aspect of the present invention, there is provided an aluminum product. The Aluminum product may comprise an aluminum substrate configured to include a pattern and a white aluminum fluoride (AlF₃) film on a surface thereof; and an anodized film configured to be disposed adjacent to the white aluminum fluoride (AlF₃) film and include a plurality of pores.

The pattern may be configured to have a roughness in a range of 5 to 100 nm.

The pattern and the white aluminum fluoride (AlF₃) film may be configured to be formed by exposing the aluminum substrate to a solution containing at least one selected from the group consisting of fluorine ions, ammonium hydrogen fluoride, potassium hydrogen fluoride, sodium hydrogen fluoride, ammonium fluoride, potassium fluoride, sodium fluoride, hydrofluoric acid, sodium borofluoride, potassium borofluoride, ammonium borofluoride, titanium potassium fluoride, titanium sodium fluoride, and titanium ammonium fluoride.

The anodized film may be configured to be formed through an anodizing process by exposing the aluminum substrate to an anodizing liquid.

The anodizing liquid may be configured to include at least one of an acid solution and a mixture of the acid solution and an acrylic resin added to the acid solution.

The acrylic resin may be at least one selected from the group consisting of hydroxypropyl methacrylate, neopentanediol dimethacrylate, and polypropylene glycol methacrylate.

The anodized film is configured to include the plurality of pores colored with a dye on an inside thereof.

The dye may be configured to be used for coloring in a form of a dispersion in an acrylic resin contained in an inside of the plurality of pores.

According to another aspect of the present invention, there is provided a method of anodizing aluminum. The method comprises modifying a surface of an aluminum substrate; whitening the aluminum substrate by exposing the aluminum substrate to a solution containing fluorine ions to form a pattern on a surface of the aluminum substrate and forming a white AlF₃ film; and forming an anodized film including a plurality of pores by anodizing the aluminum substrate in an anodizing liquid containing an acid solution.

The formation of a pattern on a surface of the aluminum substrate may include forming a pattern having a roughness in a range of 5 to 100 nm.

The formation of a pattern on a surface of the aluminum substrate may include forming a pattern by etching the aluminum substrate with the solution containing fluorine ions.

The formation of a pattern on a surface of the aluminum substrate may include forming a pattern on the surface of the aluminum substrate by exposing the aluminum substrate to a solution containing at least one selected from the group consisting of ammonium hydrogen fluoride, potassium hydrogen fluoride, sodium hydrogen fluoride, ammonium fluoride, potassium fluoride, sodium fluoride, hydrofluoric acid, sodium borofluoride, potassium borofluoride, ammonium borofluoride, titanium potassium fluoride, titanium sodium fluoride, and titanium ammonium fluoride.

The anodizing liquid may be configured to further include an acrylic resin in addition to the acid solution.

The acrylic resin may be at least one selected from the group consisting of hydroxypropyl methacrylate, neopentanediol dimethacrylate, and polypropylene glycol methacrylate.

The method may further comprise providing a dye to the plurality of pores.

The method may further comprise providing a mixture of an acrylic resin and a dye to the plurality of pores.

The method may further comprise heat-treating the surface of the aluminum substrate.

The method may further comprise ultraviolet curing the surface of the aluminum substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects of the disclosure will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a cross-sectional view of an aluminum product 100 in accordance with one embodiment of the present disclosure.

FIG. 2 is a cross-sectional view of an aluminum product 100-1 in accordance with another embodiment of the present disclosure.

FIG. 3 is a flowchart illustrating a method of anodizing aluminum in accordance with one embodiment of the present disclosure,

FIG. 4 is a schematic view for illustrating a method of anodizing aluminum in accordance with one example of the one embodiment of the present disclosure, and

FIG. 5 is a schematic view for illustrating a method of anodizing aluminum in accordance with another example of the one embodiment of the present disclosure.

FIG. 6 shows a surface of the aluminum substrate 110 before whitening,

FIG. 7 is a roughness analysis result of the surface of the aluminum substrate 110 before whitening,

FIG. 8 shows the surface of the aluminum substrate 110 after whitening, and

FIG. 9 is a roughness analysis result of the surface of the aluminum substrate after whitening.

FIG. 10 is a flowchart illustrating a method of anodizing aluminum in accordance with another embodiment of the present disclosure,

FIG. 11 is a schematic view for illustrating a method of anodizing aluminum in accordance with an example of the another embodiment of the present disclosure,

FIG. 12 is a schematic view for illustrating a method of anodizing aluminum in accordance with another example of the another embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to a method of anodizing aluminum and an article manufactured thereby in accordance with embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings.

FIG. 1 is a cross-sectional view of an aluminum product 100 in accordance with one embodiment of the present disclosure.

Referring to FIG. 1, the aluminum product 100 in accordance with one embodiment of the present disclosure may include an aluminum substrate 110, an aluminum fluoride (AlF₃) film 120 disposed adjacent to the aluminum substrate 110, and an anodized film 130 disposed adjacent to the AlF₃ film 120.

The aluminum substrate 110 may be prepared using high-purity aluminum with a purity of 99.99% or more or pure aluminum with a purity of 99% (e.g. A 1050 and A 1100). Also, in one or more embodiments of the present disclosure, the aluminum substrate 110 may be an aluminum alloy substrate. For example, the aluminum substrate 110 may be prepared using an Al—Mn alloy (e.g. A 3003 and A 3004), an Al—Mg alloy (e.g. A 5005, A 5052, and A5083), an Al—Si alloy (e.g. A 4043); an Al—Cu alloy (e.g. A 2017 and A 2024), an Al—Zn alloy (e.g. A 7072), or an Al—Mg—Si alloy (e.g. A 6061 and A 6063). Hereinafter, the aluminum substrate 110 discussed herein may be prepared using pure aluminum or an aluminum alloy.

The aluminum substrate 110 may be configured to have a plate shape, a hollow shape that is partially open, a cylindrical shape that has a bottom portion, a block shape (e.g. in the case of a cast product or a die-cast product), or the like, but the shape of the aluminum substrate 110 is not limited to the examples listed above. In FIG. 1, an aluminum substrate 110 configured to have a plate shape is provided as an example for convenience of explanation, and descriptions will be provided based on this example.

One surface of the aluminum substrate 110 is provided with a pattern and the AlF₃ film 120. The pattern and the AlF₃ film 120 may be formed by a whitening process of the aluminum substrate 110. Here, the whitening process of aluminum may refer to a process of forming a thin film and a pattern for realizing whiteness on the aluminum surface. A method of forming the pattern and the AlF₃ film 120 will be described in detail in a related section.

The aluminum substrate 110 is configured to attain a certain range of surface roughness due to the pattern formed on one surface thereof. For example, a patterned region of the aluminum substrate 110 may have a surface roughness in a range of about 5 to 100 nm. As a result, light incident on the aluminum substrate 110 is diffusely reflected on the substrate surface, thus realizing whiteness on a surface of the aluminum product 100.

One surface of the AlF₃ film 120 disposed on the aluminum substrate 110 is provided with the anodized film 130. Although in FIG. 1, the AlF₃ film 120 and the anodized film 130 are illustrated as separate components, it goes without saying that the AlF₃ film 120 and the anodized film 130 may be provided in a mixed form.

The anodized film 130 is disposed adjacent to the AlF₃ film 120 and may be configured to include a plurality of pores H therein. The pores H could be micropores H, which have the size of the pores H ranges from several to several hundred nanometers, and, if necessary, the width and depth of the pores H may be adjusted by controlling the voltage applied during an anodizing process. The anodized film 130 may be formed by the anodizing process described below, and details thereof will be described below in a related section.

FIG. 2 is a cross-sectional view of an aluminum product 100-1 in accordance with another embodiment of the present disclosure.

Referring to FIG. 2, the aluminum product 100-1 in accordance with another embodiment of the present disclosure may include an aluminum substrate 110, an AlF₃ film 120 disposed adjacent to the aluminum substrate 110, and an anodized film 130 disposed adjacent to the AlF₃ film 120. In describing the aluminum product 100-1 with reference to FIG. 2, any duplicate description of the aluminum substrate 110 and AlF₃ film 120 as compared to FIG. 1 will be omitted. Hereinafter, the aluminum product 100-1 will be described by focusing on differences with the aluminum product 100 of FIG. 1 in terms of the anodized film 130.

Like the anodized film 130 of the aluminum product 100 in accordance with FIG. 1, the anodized film 130 of the aluminum product 100-1 in accordance with FIG. 2 may be configured to have a plurality of micropores H therein, and the micropores H may be configured to be several to several hundred nanometers in size. An inside of the micropores H of the anodized film 130 in accordance with the present embodiment of the present disclosure may be colored with a dye D. The dye D may be provided as a dispersion in an acrylic resin A, and provided in such a way that a structure thereof can be fixed by the acrylic resin A so that a structural change thereof is delayed.

The dye D may be an organic dye, but the type of the dye D is not limited thereto. Also, the acrylic resin A may be methacrylic acid or a mixture containing methacrylic acid, and, more particularly, the acrylic resin A may be at least one selected from the group consisting of hydroxypropyl methacrylate, neopentanediol dimethacrylate, and polypropylene glycol methacrylate, but examples of the acrylic resin A are not limited to those listed above.

Next, a method of anodizing aluminum for manufacturing the aluminum product 100 in accordance with FIG. 1 and the aluminum product 100-1 in accordance with FIG. 2 will be described.

The method of anodizing aluminum in accordance with the present disclosure may include a process of whitening aluminum or a process for improving the light stability of an aluminum surface. For convenience of explanation, a method of anodizing aluminum including a process of whitening aluminum will be described hereinafter, and then a method of anodizing aluminum including a process of improving the light stability of an aluminum surface will be described in detail.

FIG. 3 is a flowchart illustrating a method of anodizing aluminum in accordance with one embodiment of the present disclosure, FIG. 4 is a schematic view for illustrating a method of anodizing aluminum in accordance with one example of the one embodiment of the present disclosure, and FIG. 5 is a schematic view for illustrating a method of anodizing aluminum in accordance with another example of the one embodiment of the present disclosure.

As shown in FIGS. 3 to 5, the method of anodizing aluminum in accordance with the one embodiment of the present disclosure includes a surface modification process 200 of an aluminum substrate 110; a whitening process 210 that includes exposing the aluminum substrate 110 to a solution containing fluoride ions to form a pattern on a surface of the substrate and forming a white AlF₃ film 120; and a process 220 of forming an anodized film 130 including a plurality of micropores H, by which the aluminum substrate 110 is subjected to an anodizing process in an anodizing liquid containing an acid solution.

The surface modification process 200 of the aluminum substrate 110 is a process by which a surface of the aluminum substrate 110 is exposed to a pretreatment liquid to remove impurities from the surface of the aluminum substrate 110. The surface modification process 200 of the aluminum substrate 110 may be degreasing treatment, etching treatment, chemical polishing treatment, desmutting treatment, or the like.

As the pretreatment liquid, an acidic pretreatment solution or basic pretreatment solution may be used. For example, the pretreatment liquid used for the degreasing treatment may be a sulfuric acid solution, a sodium hydroxide solution, or a solution containing a mixture of sodium phosphate, sodium borate, and sodium carbonate. Also, a solution containing a mixture of sodium hydroxide and sodium gluconate, a solution containing a mixture of phosphoric acid and sulfuric acid, or the like may be used for the etching treatment. In the chemical polishing treatment, at least one solution selected from the group consisting of phosphoric acid solutions, sulfuric acid solutions, and nitric acid solutions may be used. Also, in the desmutting treatment, a sulfuric acid solution, a nitric acid solution, or the like may be used. However, the type of the pretreatment liquid is not limited to those listed above and may include modifications within a range that can be easily conceived by those skilled in the art.

The surface modification process 200 of the aluminum substrate 110 may be a process of removing an organic substance present on a surface of the aluminum substrate 110, a process of removing a natural oxide film, a process of removing smut (desmutting), and the like. In this case, desmutting refers to an act of removing smut that is generated on a substrate surface during pickling or alkali immersion.

The surface modification process 200 of the aluminum substrate 110 may be followed by the whitening process 210. The whitening process 210 in accordance with the present disclosure is for realizing long-term whiteness on a surface of the aluminum product 100, and may include a process of exposing the surface-modified aluminum substrate 110 to a whitening liquid.

A solution containing fluoride ions may be used as the whitening liquid. It goes without saying that, for example, a solution containing at least one selected from the group consisting of ammonium bifluoride, ammonium hydrogen fluoride (NH4HF2), potassium hydrogen fluoride, sodium hydrogen fluoride, ammonium fluoride, potassium fluoride, sodium fluoride, hydrofluoric acid, sodium borofluoride, potassium borofluoride, ammonium borofluoride, titanium potassium fluoride, titanium sodium fluoride, and titanium ammonium fluoride or a mixture thereof may be used.

The whitening liquid forms a white AlF₃ film 120 by reacting with aluminum, and, at the same time, realizes a pattern on a surface of the aluminum substrate 110 by etching the surface.

In the present embodiment of the present disclosure, a 50 g/L ammonium fluoride solution was used as the whitening liquid, and the whitening process was carried out by immersing a surface-modified aluminum substrate 110 in the ammonium fluoride solution at about 30° C. for about three minutes. Once the aluminum substrate 110 was exposed to the whitening liquid, the surface of the aluminum substrate 110 was etched, thus leaving a pattern, and an AlF₃ film 120 was formed on the etched surface of the aluminum substrate 110.

As described above, a pattern is formed on a surface of the aluminum substrate 110 as the substrate undergoes the whitening process. When light is incident on the substrate surface, the incident light is diffusely reflected on a surface of the pattern, thus resulting in the realization of whiteness on the aluminum product 100 surface.

For example, a surface of the aluminum substrate 110 after the whitening process may have roughness within a range of about 5 to 100 nm. Hereinafter, roughness analysis results of the aluminum substrate 110 before and after whitening will be discussed with reference to accompanying drawings.

FIGS. 6 to 9 show roughness analysis results of the aluminum substrate 110 before and after whitening. More specifically, FIG. 6 shows a surface of the aluminum substrate 110 before whitening, FIG. 7 is a roughness analysis result of the surface of the aluminum substrate 110 before whitening, FIG. 8 shows the surface of the aluminum substrate 110 after whitening, and FIG. 9 is a roughness analysis result of the surface of the aluminum substrate 110 after whitening.

Referring to FIGS. 6 to 9, it can be seen that a surface of the aluminum substrate 110 has greater smoothness before whitening as compared to the same after whitening. In other words, the surface of the aluminum substrate 110 shown in FIG. 6 is found to be smoother than the surface of the aluminum substrate 110 shown in FIG. 8.

Also, based on the roughness analysis result of each surface, the surface roughness of the aluminum substrate 110 before whitening as shown in FIG. 7 is about 9.1 nm, and the surface roughness of the aluminum substrate 110 after whitening as shown in FIG. 9 is about 44.3 nm. In other words, the surface roughness of the aluminum substrate 110 after whitening is found to be greater than the surface roughness of the same before whitening.

Provided below are results of component analysis of the aluminum substrate 110 before whitening (Table 1) and after whitening (Table 2).

TABLE 1 Component Weight % Atomic % C 8.06 16.07 O 3.75 5.61 F 0.00 0.00 Mg 0.27 0.26 Al 87.55 77.73 Si 0.38 0.32 Total 100.00 100.00

TABLE 2 Component Atomic % C 49.13 N 1.49 O 19.85 F 14.19 Al 10.48 Si 2.57 S 0.47 Cl 0.95 Ca 0.86 Total 100.00

As shown in Tables 1 and 2, the content of fluorine (F) in the aluminum substrate 110 increases from 0.00 atomic % to 14.19 atomic % through whitening. In other words, component analysis results of the aluminum substrate 110 before and after whitening confirm the formation of an AlF₃ film 120 on a surface of the aluminum substrate 110.

Once the whitening process of the aluminum substrate 110 is completed, a subsequent process 220 of anodizing the aluminum substrate 110 may be carried out.

Anodization is an electrochemical treatment method in which a part to be treated is used as an anode and placed in a suitable solution and sufficiently high voltage necessary for oxygen overpotential is applied to the solution to cause oxygen to be adsorbed on a surface of the anode. When ions in the solution react with the oxygen on the metal surface, an oxide film exhibiting good adhesion is formed. For example, when the aluminum substrate 110 is subjected to anodization, an oxide film (Al2O3) is formed on a surface of the aluminum substrate 110. Hereinafter, the oxide film formed on the surface of the aluminum substrate 110 is referred to as an anodized film 130 for convenience of explanation.

Being compact and strong, the anodized film 130 protects the interior metal. Hence, the anodized film 130 formed after the formation of the AlF₃ film 120 may enhance the durability of the AlF₃ film 120. Also, by being porous and transparent or semitransparent, the anodized film 130 may be dyed in one or more of various colors, and the excellent corrosion resistance thereof helps to maintain the realized color(s) for a long time. In general, the higher the purity of aluminum in the aluminum substrate 110, the more aesthetically pleasing and glossy the obtained film can be.

The process of forming the anodized film 130 will be described in more detail as follows: First, the aluminum substrate 110 is exposed to an anodizing liquid containing an acid solution. In one or more embodiments of the present disclosure, the anodizing liquid may be an acid solution containing an acrylic resin A added thereto. Examples of the acid solution may include sulfuric acid solutions, but examples of an acceptable acid solution are not limited thereto. Depending on the addition of the acrylic resin A to the anodizing liquid, the method for enhancing the light stability of the aluminum substrate 110 afterwards may vary. Details thereof will be described below in a related section.

Once the aluminum substrate 110 is placed in an anodizing liquid containing an acid solution, current is released by using the aluminum substrate 110 as an anode. When current is released, an aluminum oxide film is formed at an early stage, and the subsequent application of sufficient voltage results in the formation of a porous anodized film 130 having a plurality of micropores H. Considering that the current is maintained constant by direct current voltage, the voltage is preferably adjusted within a range of about 1 to 30 V, and the duration of oxidation depends on the voltage level.

When the aluminum substrate 110 is anodized in an anodizing liquid containing an acid solution, an aluminum product 100 with the same cross section as the last stage of FIG. 4 may be realized. That is, a porous anodized film having a plurality of micropores H is formed on the aluminum substrate 110.

When the aluminum substrate 110 is anodized in an anodizing liquid prepared by adding an acrylic resin A to an acid solution in accordance with one embodiment of the present disclosure, an aluminum product 100 with the same cross section as the last stage of FIG. 5 may be realized. In other words, a porous anodized film 130 configured to include a plurality of micropores H filled with the acrylic resin A is formed on the aluminum substrate 110. If necessary, the acrylic resin A may be removed by way of washing with water, or, in accordance with one or more embodiments of the present disclosure, another substance may be added to the acrylic resin A to cause the substance to cure together with the acrylic resin A.

Next, a method of anodizing aluminum and an aluminum product 100 in accordance with another embodiment of the present disclosure will be described.

The method of anodizing aluminum in accordance with the present embodiment of the present disclosure relates to a method of realizing one or more of various colors in the aluminum product 100 that has been prepared in white in accordance with the aforementioned method and enhancing the light stability of the realized color(s). The method of realizing color(s) and enhancing the light stability of the realized color(s) in accordance with the present embodiment of the present disclosure may be used for realizing color(s) and enhancing light stability in a porous material having a plurality of micropores H and for other purposes within a range that can be easily conceived by those skilled in the art.

Hereinafter, for convenience of explanation, a method for realizing color(s) and enhancing the light stability of the realized color(s) will be described based on the white aluminum product 100 as shown in FIG. 1. The method of anodizing aluminum in accordance with the present embodiment of the present disclosure aims to color the aluminum product 100, which has been prepared in white, as the target. In this case, one or more of various colors, for example, light colors such as pastel colors, may be realized by varying the type and amount of the dye D. Hereinafter, embodiments of the present disclosure will be described in detail with reference to accompanying drawings.

FIG. 10 is a flowchart illustrating a method of anodizing aluminum in accordance with another embodiment of the present disclosure, FIG. 11 is a schematic view for illustrating a method of anodizing aluminum in accordance with an example of the another embodiment of the present disclosure, and FIG. 12 is a schematic view for illustrating a method of anodizing aluminum in accordance with another example of the another embodiment of the present disclosure.

As shown in FIGS. 10 to 12, the method of anodizing aluminum in accordance with the another embodiment of the present disclosure may include a surface modification process 200 of an aluminum substrate 110; a whitening process 210 that includes exposing the aluminum substrate 110 to a solution containing fluoride ions to form a pattern on a surface of the substrate and forming a white AlF3 film 120; a process 220 of forming an anodized film 130 having a plurality of pores H, by which the aluminum substrate 110 is subjected to an anodizing process in an anodizing liquid containing an acid solution; and a coloring process 230 by which a dye D is provided to the plurality of pores H.

Since the surface modification process, whitening process, and process of forming an anodized film described above are substantially the same as those discussed in FIG. 1, the coloring process, which was not discussed in FIG. 1, will be mainly described hereinafter.

FIG. 11 is a schematic view for illustrating a method of anodizing aluminum when an acid solution is used as an anodizing liquid for the anodizing process.

As described above, an aluminum product 100 with the same cross section as the fourth stage of FIG. 11 is manufactured when an acid solution is used as the anodizing liquid for the anodizing process. In other words, when the anodizing process is carried out using the anodizing liquid in accordance with the present embodiment of the present disclosure, a porous anodized film 130 including a plurality of pores H is formed.

Once the anodized film 130 is formed, a coloring process 230 of the aluminum substrate 110 is carried out. The coloring process 230 of the aluminum substrate 110 may include a process of exposing the aluminum substrate 110 to a coloring liquid.

As the coloring liquid, an aqueous solution containing a mixture of an organic dye and an acrylic resin A may be used. As the acrylic resin A, methacrylic acid or a mixture containing methacrylic acid may be used, and more specifically, at least one selected from the group consisting of hydroxypropyl methacrylate, neopentanediol dimethacrylate, and polypropylene glycol methacrylate may be used. However, the type of the coloring liquid is not limited to those listed above.

The coloring process 230 of the aluminum substrate 110 may be carried out in such a way that the aluminum substrate 110 is immersed in the coloring liquid. When the aluminum substrate 110 is immersed in the coloring liquid, the dye D and the acrylic resin A are adsorbed onto an inside of pores H of the anodized film 130 through a capillary phenomenon and charge interactions. Subsequently, the polymerization of the acrylic resin A causes the structure of the dye D to be fixed. This may delay a phenomenon in which the structure of the dye D is altered by light, and prevent the discoloration of the dye D.

Once the coloration process is completed, a process of polymerizing the acrylic resin A is carried out. The process of polymerizing the acrylic resin A is a process for promoting the polymerization of the acrylic resin A contained inside the pores H, and may include, for example, a heat-treatment process and/or an ultraviolet curing process. In carrying out the process of polymerizing the acrylic resin A, only one of the heat-treatment process and the ultraviolet curing process may be carried out, or, in one or more embodiments of the present disclosure, the heat-treatment process and the ultraviolet curing process may be carried out in a simultaneous or sequential manner.

During the heat-treatment process, heat in the range of 50 to 300° C. may be applied to promote the polymerization of the acrylic resin A. When sufficient amount of heat is applied to the acrylic resin A, the dye D penetrates into the acrylic resin A, simultaneously promoting the polymerization of the acrylic resin A, thereby further enhancing the light stability. It goes without saying that the polymerization of the acrylic resin A can be promoted by treating the acrylic resin A with ultraviolet light in one or more embodiments of the present disclosure.

Meanwhile, it should be widely understood that examples of the polymerization process are not limited to those listed above but include modifications within a range that can be easily conceived by those skilled in the art.

FIG. 12 is a schematic view for illustrating a method of anodizing aluminum when a solution prepared by adding an acrylic resin A to an acid solution is used as an anodizing liquid for the anodizing process.

As described above, when a solution prepared by adding an acrylic resin A to an acid solution is used as the anodizing liquid for the anodizing process, an aluminum product having the same cross section as the fourth stage of FIG. 12 is manufactured. In other words, when the anodizing process is carried out using the anodizing liquid in accordance with the present embodiment of the present disclosure, an anodized film 130 in the form of a porous anodized film 130 including a plurality of pores H filled with the acrylic resin A is obtained.

Once the anodized film 130 is obtained, a process of coloring the aluminum substrate 110 with a dye D is carried out. The process of coloring the aluminum substrate 110 may include a process of exposing the aluminum substrate 110 to a coloring liquid. An organic dye may be used as the coloring liquid, but the type of the coloring liquid is not limited thereto.

For example, the process of coloring the aluminum substrate 110 may be carried out in such a way that the aluminum substrate 110 is immersed in the coloring liquid, and any duplicate description thereof as compared to FIG. 11 will be omitted. The coloring process in accordance with the present embodiment of the present disclosure differs from the method in accordance with FIG. 11 in that the dye D penetrates into the acrylic resin A, which fills an inside of the pores H in the anodized film 130, when the coloring process is carried out after anodization. In other words, a process of mixing the acrylic resin A and the dye D may be omitted, thereby improving process efficiency.

Once the coloring process is completed, a process of polymerizing the acrylic resin A may be carried out. The polymerization process in accordance with the present embodiment of the present disclosure may also include a heat-treatment process, an ultraviolet curing process, or the like, and any duplicate description thereof will be omitted hereinafter.

Although a few examples of a method of anodizing aluminum and an article manufactured thereby have been described above in detail, it should be widely understood that the technical idea of the present disclosure is not limited to the above-described examples but includes modifications within a range that can be easily conceived by those skilled in the art. 

What is claimed is:
 1. An aluminum product, comprising: an aluminum substrate configured to include a pattern and a white aluminum fluoride (AlF₃) film on a surface thereof; and an anodized film configured to be disposed adjacent to the white aluminum fluoride (AlF₃) film and include a plurality of pores.
 2. The aluminum product according to claim 1, wherein the pattern is configured to have a roughness in a range of 5 to 100 nm.
 3. The aluminum product according to claim 1, wherein the pattern and the white aluminum fluoride (AlF₃) film are configured to be formed by exposing the aluminum substrate to a solution containing at least one selected from the group consisting of fluorine ions, ammonium hydrogen fluoride, potassium hydrogen fluoride, sodium hydrogen fluoride, ammonium fluoride, potassium fluoride, sodium fluoride, hydrofluoric acid, sodium borofluoride, potassium borofluoride, ammonium borofluoride, titanium potassium fluoride, titanium sodium fluoride, and titanium ammonium fluoride.
 4. The aluminum product according to claim 1, wherein the anodized film is configured to be formed through an anodizing process by exposing the aluminum substrate to an anodizing liquid.
 5. The aluminum product according to claim 4, wherein the anodizing liquid is configured to include at least one of an acid solution and a mixture of the acid solution and an acrylic resin added to the acid solution.
 6. The aluminum product according to claim 5, wherein the acrylic resin is at least one selected from the group consisting of hydroxypropyl methacrylate, neopentanediol dimethacrylate, and polypropylene glycol methacrylate.
 7. The aluminum product according to claim 1, wherein the anodized film is configured to include the plurality of pores colored with a dye on an inside thereof.
 8. The aluminum product according to claim 7, wherein the dye is configured to be used for coloring in a form of a dispersion in an acrylic resin contained in an inside of the plurality of pores.
 9. A method of anodizing aluminum, comprising: modifying a surface of an aluminum substrate; whitening the aluminum substrate by exposing the aluminum substrate to a solution containing fluorine ions to form a pattern on a surface of the aluminum substrate and forming a white AlF₃ film; and forming an anodized film including a plurality of pores by anodizing the aluminum substrate in an anodizing liquid containing an acid solution.
 10. The method according to claim 9, wherein the formation of a pattern on a surface of the aluminum substrate includes forming a pattern having a roughness in a range of 5 to 100 nm.
 11. The method according to claim 9, wherein the formation of a pattern on a surface of the aluminum substrate includes forming a pattern by etching the aluminum substrate with the solution containing fluorine ions.
 12. The method according to claim 9, wherein the formation of a pattern on a surface of the aluminum substrate includes forming a pattern on the surface of the aluminum substrate by exposing the aluminum substrate to a solution containing at least one selected from the group consisting of ammonium hydrogen fluoride, potassium hydrogen fluoride, sodium hydrogen fluoride, ammonium fluoride, potassium fluoride, sodium fluoride, hydrofluoric acid, sodium borofluoride, potassium borofluoride, ammonium borofluoride, titanium potassium fluoride, titanium sodium fluoride, and titanium ammonium fluoride.
 13. The method according to claim 9, wherein the anodizing liquid is configured to further include an acrylic resin in addition to the acid solution.
 14. The method according to claim 13, wherein the acrylic resin is at least one selected from the group consisting of hydroxypropyl methacrylate, neopentanediol dimethacrylate, and polypropylene glycol methacrylate.
 15. The method according to claim 9, further comprising providing a dye to the plurality of pores.
 16. The method according to 15, further comprising providing a mixture of an acrylic resin and a dye to the plurality of pores.
 17. The method according to claim 15, further comprising heat-treating the surface of the aluminum substrate.
 18. The method according to claim 15, further comprising ultraviolet curing the surface of the aluminum substrate. 